Explosive-forming apparatus



Dec. 21, 1965 E. K. HENRIKSEN 3,224,238

EXPLOSIVE-FORMING APPARATUS Filed Aug. 29, 1963 INV OR ERIK K. HENR|KSENg8 By ATTO EY United States Patent 3,224,238 EXPLOSIVE-FORMING APPARATUSErik K. Henricksen, Downey, Calif., assignor to Aerojet- GeneralCorporation, Azusa, Califl, a corporation of Ohio Filed Aug. 29, 1963,Ser. No. 305,295

10 Claims, (Cl. 72-56),

The present invention relates in general to the art of die-shaping andmore particularly to a method of and apparatus for shaping through theuse of forcing means such as explosives.

In explosive forming or shaping, the workpiece is positioned in a diewhich may be immersed in a tank of fluid such as water. An explosivealso is immersed which when detonated will bring the workpiece to thedesired shape by shock waves transmitted through the liquid driving theworkpiece against the die. Gases generated by the detonation of theexplosive are free to escape from the die and have no effect on theoperation.

When tubular dies are used to form a workpiece to accurate dimensions,it is necessary that the explosive be positioned axially within the diewith a high degree of accuracy. Such axial positioning has beendifiicult to accomplish, and it is toward removing difliculties inpositioning that this invention is directed.

Accordingly, it is an object of this invention to provide a method ofand means for positioning an explosive accurately in a tubular die whichis both rapid and effective.

It is another object of the invention toprovide a method of and meansfor such positioning wherein centering of the explosive is accomplishedquickly and easily by means external to the explosion chamber.

It is a still further object of the invention to provide a method of andmeans for accurately positioning an explosive in a tubular die whichmeans may be rapidly operated by unskilled personnel without danger offaulty operation.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

FIG. 1 is a side elevation partly in section of one embodiment of theinvention.

FIG. 2. is a section along line 22 in FIG. 1.

FIG. 3 is an end view of a component of the embodiment shown in FIG. 1.

FIG. 4 is a sectional view of a component of an alternate embodiment ofthe invention.

FIG. 5 is a view partly in section of a companion memher to thecomponent shown in FIG. 4.

FIG. 6 is a view partly in section of components of an alternateembodiment of the invention.

Referring now to FIG. 1, a sectional cylindrical die 10 is shown whichincludes semi-cylindrical sections 11 and 12, the die 10 configured toform workpiece 16 into desired shape. Several identical sections ofsimilar workpieces may be formed and joined by welding, brazing or othermeans.

Flanges 13 and 14 may be clamped together by bolts and nuts 15 or byother suitable means. Explosive 17, if it is to form identical sections,must be positioned accurately axially in die 10 and may be a rod ofexplosive or a length of Primacord or a number of explosive segmentspositioned end to end. Explosive 17 is suspended generally centrallywithin die 10 by cords or wires 27'whose ends are secured to die endmembers 20 and; 21.. End member 20 may be formed as a disc fittingwithin the end of die 10 for the purpose of accurate centering andhaving a flange 22 abutting the end surface of the die. The inner faceof end member 20 may be formed with an axial recess 23 which has ascrewthreaded wall 24. A support retainer comprising a ring 25 havingits outer edge screw-threaded to screw into recess 23 is formed with aplurality of slots 26, shown in FIG. 3, extending inwardly from the.center opening of ring 25, the center opening being slightly greater indiameter than the diameter of the explosive or Primacord.

A plurality of extensible means such as cords 27 shown in FIG. 2, withknots at their ends, or headed wires of equal length, are positioned onein each of slots 26 and retained therein by a retaining sleeve 28, shownin FIG.3, having an inner diameter slightly greater than that of theexplosive. The outer diameter of sleeve 28 fits snugly within the ring25. Sleeve 28 is provided with an outwardly projecting flange 29overlying the end knots of the extensible means 27. The outer face ofend member 20 is formed with a center boss 30 axially drilled to closelyfit a squib 31 crimped onto the length of explosive 17. A retaining ring32 screwing onto the outside of hub 30 clamps the length of explosive 17in position.

The opposite end members 20, 21 are cut away on opposite sides as shownat 33 in FIG. 2, to facilitate assembly and operation and to provide forthe escape of gases generated by the detonation of the explosive 17.Spring clips 34 may be mounted on the ends of the die to initiallymaintain the end members 20, 21, in position, the clips, 34 beingarranged to permit assembly and rotation of. the end'members.

The support retaining arrangement associated with end member 21 includesa threaded stem 35 which is formed with spline teeth 36 at its inner endto engage with splines 36 at the inner end of an axial bore in endmember 21. Slots 37 are cut between the teeth 36 and lead into aperipheral recess 38. The remainder of the stem 35 is threaded. Aretaining sleeve 39 is interiorly threaded to screw on the stem 35 toretain end knobs on extensible means or cords 27 in the recess 38.

End member 21 is formed with an outwardly extending central boss 40drilled to receive stem 35 and is furnished with a stepped end 41. Atightening hand wheel 42 fits on the stepped end 41 and is provided withan axial interiorly threaded bore engaging with the threaded stem 35;When hand-wheel 42 is rotated, stem 35 is moved outwardly stretchingtight the cords 27, the spline teeth 36 sliding along the splines 36 cutaround the inner end of the hole drilled through boss 40.

When the cords have been stretched tight they may be wound helicallyaround the surface of the rod of explosive by rotating one or both theend members 20, 21, in the latter case, of course, in oppositedirections.

In FIGS. 4 and 5 analternate embodiment of the invention is shownwherein support and positioning of the explosive is eifected through useof a loosely woven fabric sleeve whose end strands are secured to endmembers 20 and 21. Explosive 17 is inserted through alternate end member43 which is formed as a ring and threaded on its outer periphery toscrew into the recess 23 shown in FIG. 1. Member 43 is provided with aninwardly extending boss 44 having a peripheral groove 45 to receive acord 46 by which one end of a loosely woven fabric tube 47 is secured onthe boss 44.

The member 48 securing the opposite end of the fabric sleeve 47 includesa threaded stem 49 at itinner end and a projection 58* having aperipheral groove 51 to which the opposite end of sleeve 47' is securedby cord 52 as in FIG; 4. Interposed between the projection 50 and thethreaded portion 49 of the member are spline teeth 53 formed to engagewith the spline grooves 36 formed at the inner end of the bore in endmember 21 as shown in FIG. 2.

Threads 49 will be engaged by the interior thread on hand-wheel 42 asshown in FIG. 1, and since member 47 forms a sheath for the explosive inslack condition, merely stretching the member 47 is sufficient toprovide a firm support centralizing the rod of explosive, particularlywhere the fabric is woven of diagonally arranged threads. Instead of aloosely woven fabric tube 47, a length of rubber tube may be used, whichalso will contract in diameter when stretched.

FIG. 6 shows a third embodiment of the invention in which the endmembers of the die are used to support and apply tension to a rod ofexplosive having formed integral ly with it a surrounding or interwovengrid, net or tube which sustains a diametrical contraction whenstretched. The end members 20 and 21 shown in FIG. 1 are used with onlyadditional member 54 necessary at each end of the die. Member 54 isformed with an axial stub 55 having a bore 56 cylindrical at its outerend and of square cross-section at its inner end, the square crosssection of the bore tapering inwardly. The outer surface of stub 55 isscrew-threaded as shown at 57 and a hand wheel 58 may be mounted on thethreaded section. The center portion of the hub of the hand wheel isdrilled out as indicated at 59. A square tubular key 60 tapered at itsinner end and slotted so that it may be forced to make a solidconnection between the wall of the square section of the hole in endmember 54 and a square section of rod 61 of a suitable explosive istightened by hand wheel 58. A squib 62 pinched onto a short cylindricalend portion of the explosive 61 has a terminal 63 projecting through thecenter opening in the hand wheel 58.

The rim of the end piece 54, which may be similar in configuration tothat of the end members previously described, is provided with aplurality of small holes aligning with axially extending holes drilledinto the edge of the die. A small pin 64 may be inserted through a holein the edge of the end member 54 and into a hole in the die memberaligned therewith until it is required to twist the rod of explosive bytwisting the end member 54 about the axis of the die. After putting therod of explosive 61 under the required torsion, the pin 64 may bereinserted to maintain the desired torsion.

Since the die is lowered below the surface of liquid in a tank, combinedhoisting lugs 65 and legs 66 (see FIG. 2) are attached to the die toenable it to be positioned in a tank (not shown) either vertically orhorizontally as may be required.

In describing operation of the device it will be assumed that the die issupported out of a tank (not shown) and has been assembled by tighteningup the bolts and nuts 15 and with end members 20, 21 removed. Theworkpiece 16 is then inserted in placed. Cords 27 are then connected toend member 20 by laying them in slots 26 in ring 25, which has beenremoved from the end member 20, and retained in position by retainingsleeve 28. The loaded ring is then screwed into the recess 23. Threadedstem 35, which has been removed from end member 21, is then connected tothe free ends of cords 27 and held in place by screwing sleeve 39 on thethreaded stem to retain the knotted end of the cords in the recess 38,and the hand Wheel 42 is screwed off the stem 35. A length of rod(serving as a positioning tool) may then be passed through end member 20and engaged against the stem 35, the extended cords surrounding the rod.End member 20 is then positioned in the end of the die.

Threaded stem 35 may be readily guided into the axial bore in end member21, which is in position in the opposite end of the die, the splineteeth 36 entering splines 36' and restricting stem 35 to axial movementrelative to end member 21. Spring clips 34 serve to retain the endmembers in position at this stage of the assembly. The hand wheel isthen screwed on the outer end of the threaded stem until in position onthe outer end of boss 40 and then tightened up to initially stress thecords or wires 27.

The positioning rod is then withdrawn and the explosive inserted. Theexplosive is positioned by screwing ring 32 down on squib 31, and maythen be firmly gripped in axial alignment by rotating the end members20, 21 with respect to one another which has the effect of both wrappingthe cords 27 helically around the rod of explosive and furthertightening them.

The assembled die with the workpiece and explosive axially aligned isthen lowered to a position below the level of the liquid in the tank andconventional procedures are followed in exploding the charge. A similarprocedure is followed with respect to the embodiments of FIGS. 4 and 5,sheath 47 being positioned before explosive 17 is inserted within it.

In the modification of the invention shown in FIG. 6, one end ofexplosive 61 may be mounted in an end member 54 after hand wheel 58 hasbeen slacked back or unscrewed and key 60 knocked out. Key 60 is thenreplaced and forced into the square bore in the end member 54 byscrewing up the hand wheel to force the squared resilient end of key 60between the squared periphery of the rod 61 and the faces of the squaresocket in the end member 54. The end member carrying the rod 61 by oneend is then inserted in the die and the free end fitted in the centeropening in the other end member from which the chuck member and handwheel have been removed. This end member is then positioned on the endof the die and the chuck member positioned in the socket and firmlyseated by screwing up the hand wheel. The rod 61 if explosive may thenbe put under torsion by twisting one or both of the end members whichend members can be retained in position by inserting pin 64 into alignedholes in the edge of the die and end member. Torsion will then shorten,tighten and straighten the rod of explosive axially within the die.

After the explosive has been centered by any of the means shown anddescribed, an electric cable controlled by a make and break switch inthe usual manner may be connected to the contact extending from a squibsecured on one end of the explosive. The explosive may then be detonatedby closing the switch after the die has been positioned in a tank ofliquid.

Where it is desired to form workpiece 16 under a vacuum, O-rings 70 and71 may be positioned between the workpiece and end members 20 and 21 toform a vacuum tight seal therebetween. Vacuum fitting 73 is then addedto provide a passage through which a vacuum may be created in the space72 between the outer periphery of workpiece 16 and die 10. Conventionalevacuating means, not shown, may then be connected to passage 74 invacuum fitting 73, and space 72 evacuated.

It will be appreciated that other means than those shown and describedmay be used to position an explosive within the concept of theinvention. For example, alternate end members 20 and 21 may be used ineach embodiment, with those for the embodiment of FIG. 1 being simplyend plates with an annular ring of holes accurately positioned in axialalignment with the die, and cords 27 drawn taut through the holes andknotted at the outer surfaces of the plates. Likewise, with respect tothe embodiment of FIGS. 4 and 5 where one plate may have the projection50 and groove 51 shown in FIG. 5 and the other a similar groove on theend of a shaft which is threaded and extends through the outer endplate. The desired tension may then be applied by turning the shaft.Locking in position may be efifected by a lock nut turned over thethreads and abutting the outer surface of the plate. In the embodimentof FIG. 6, the alternate end plates would have axially positioned holesthrough which the integral explosive and support member would project,the portions projecting preferably being square and recured within aclamping member by means of which torsion may be applied.

Also included in the concept of the invention is the use of segments ofexplosive and segments of spacer material to be inserted in the volumeformed by the cords, sheath or other extensible means such thatexplosive segments may be positioned at desired points within theenclosed volume.

Obviously many modifications and variations of the present invention arepossible in the light of, the above teachings. the scope of the appendedclaims the invention may be practiced otherwise than as specificallydescribed.-

I claim:

1. The method of positioning a uniformly shaped member axially within auniformly shaped chamber comprising the steps of positioning said memberin a sheath whose diameter is reduced when the sheath is stretched,mounting the sheath centrally between opposed end members to saidchamber, andstretching the sheath in an axial direction by forcesapplied exterior to said chamber whereby the sheath diameter isdecreased until a desired compression against said member is realized,said compression being exerted radially inwardly so as to simultaneouslycenter said member in said chamber.

2. A device for positioning an elongate body of substantially uniformcross section centrally within an elongate chamber by externalapplication of force comprising a pair of removable end means forsubstantially enclosing said chamber, sheath means defining a volumesufiicient to freely accommodate said body, said sheath means beingsusceptible to constriction upon being extended, means for securing oneend of said sheath means central- 1y to the inner surface of one of saidend means, said other end means having an aperture centrally disposed toaccommodate said sheath means, and means extending through said aperturefor gripping the other end of and extending said sheath Within saidchamber, whereby upon positioning said body in said sheath within saidchamber, extenson of said sheath will constrict said sheath against saidbody and simultaneously center said body within said chamber.

3. Explosive-forming apparatus comprising: a tubular die, a pair of endclosure members respectively centered in the opposite ends of thetubular die, at least one of said end closure members being removablefrom said tubular die, a'rod of explosive material extending axiallythrough said tubular die, strand means secured to said end closuremembers and arranged to extend around the periphery and along the lengthof said rod of explosive material to support said rod of explosivematerial within said tubular die, and means mounted on at least one ofsaid end closure members effective to draw said strand means into tautcondition around and bearing against the surface of said rod ofexplosive material to accurately support said rod of explosive materialaxially of said tubular die.

4. Explosive-forming apparatus as set forth in claim 3, wherein saidstrand means comprises a plurality of cords extending between said endclosure members.

5. Explosive-forming apparatus as set forth in claim 3, wherein saidstrand means comprises a loosely woven fabric sleeve defining a sheathextending between said end closure members.

6. Explosive-forming apparatus comprising: a tubular die, a pair of endclosure members respectively centered in the opposite ends of thetubular die, at least one of said end closure members being removablefrom said tubular die, a rod of explosive material extending axiallythrough said tubular die, strand means secured to said end closuremembers and arranged to extend around the periphery and along the lengthof said rod of explosive material to support said rod of explosivematerial within said tubular die, means mounted on at least one of saidend closure members effective to draw said strand means into tautcondition around and bearing against the surface of said rod ofexplosive material, and at least one of said end closure members beingmounted for rotation on the end of the tubular die with which it isassociated so that said taut strand means secured to said end closuremembers It is therefore to be understood that within may be wound undertension helically around said rod of explosive material upon rotation ofsaid latter one of said end closure members to accurately support saidrod of explosive material axially of said tubular die.

7. Explosive-forming apparatus comprising: a tubular die, a pair of endclosure members respectively centered in the opposite ends of thetubular die, at least one of said end closure members being removablefrom said tubular die, a rod of explosive material extending axiallythrough said tubular die, strand means arranged to extend around theperiphery and along the length of said rod of explosive material,securing means mounted centrally on one of said end closure memberseffective to secure one end of said strand means, securing means mountedcentrally on the other of said end closure members to which the otherend of said strand means is connected, means mounting one of saidsecuring means on said end closure member with which it is associatedfor guided axial movement to bring said strand means into taut conditionaround and bearing against the surface of said rod of explosive materialwhen said one securing means is caused to move axially away from theother securing means, and at least one of said end closure members beingmounted for rotation on the end of the tubular die with which it isassociated so that said taut strand means may be wound helically aroundthe rod of explosive material upon rotation of said latter one of saidend closure members to accurately support said rod of explosive materialaxially of said tubular die.

8. Explosive-forming apparatus comprising: a tubular die, a pair of endclosure members respectively disposed at the opposite ends of thetubular die, a rod of explosive material extending axially through saidtubular die, means carried by said end closure members to support saidrod of explosive material within said tubular die, and at least one ofsaid end closure members being rotatably mounted on said tubular die,whereby rotatio of said one end closure member is effective to operatesaid supporting means carried thereby to enable said rod of explosivematerial to be accurately supported axially of said tubular die.

9. Explosive-forming apparatus comprising: a tubular die, a pair of endclosure members respectively disposed at the opposite ends of thetubular die, a rod of explosive material extending axially through saidtubular die, a plurality of cords carried by said end closure membersand extending therebetwee around the periphery and along the length ofsaid rod of explosive material to support said rod of explosive materialwithin said tubular die, and at least one of said end closure membersbeing rotatably mounted on said tubular die, whereby rotation of saidone end closure member is effective to wind said plurality of cordshelically about said rod of explosive material to enable said rod ofexplosive material to be accurately supported axially of said tubulardie.

10. Explosive-forming apparatus comprising: a tubular die, a pair of endclosure members respectively disposed at the opposite ends of thetubular die, a rod of explosive material extending axially through saidtubular die, a sheath carried by said end closure members and extendingtherebetween in surrounding relation to said rod of explosive materialto support said rod of explosive material within said tubular die, andmeans mounted on at least one of said end closure members effective tostretch said sheath for constricting said sheath about said rod ofexplosive material to enable said rod of explosive material to beaccurately supported axially of said tubular die.

References Cited by the Examiner UNITED STATES PATENTS 2,779,279 1/ 1957Maiwurm 113-44 3,162,709 12/ 1964 Davidson 25-l 18 CHARLES W. LANHAM,Primary Examiner.

2. A DEVICE FOR POSITIONING AN ELONGATE BODY OF SUBSTANTIALLY UNIFORMCROSS SECTION CENTRALLY WITHIN AN ELONGATE CHAMBER BY EXTERNALAPPLICATION OF FORCE COMPRISING A PAIR OF REMOVABLE END MEANS FORSUBSTANTIALLY ENCLOSING SAID CHAMBER, SHEATH MEANS DEFINING A VOLUMESUFFICIENT TO FREELY ACCOMMODATE SAID BODY, SAID SHEATH MEANS BEINGSUSCEPTIBLE TO CONSTRICTION UPON BEING EXTENDED, MEANS FOR SECURING ONEEND OF SAID SHEATH MEANS CENTRALLY TO THE INNER SURFACE OF ONE OF SAIDSHEATH MEANS, SAID OTHER END MEANS HAVING AN APERTURE CENTRALLY DISPOSEDTO ACCOMMODATE SAID SHEATH MEANS, AND MEANS EXTENDING THROUGH SAIDAPERTURE FOR GRIPPING THE OTHER END OF AND EXTENDING SAID SHEATH WITHINSAID CHAMBER, WHEREBY UPON POSITIONING SAID BODY IN SAID SHEATH WITHINSAID CHAMBER, EXTENSION OF SAID SHEATH WILL CONSTRICT SAID SHEATHAGAINST SAID BODY AND SIMULTANEOUSLY CENTER SAID BODY WITHIN SAIDCHAMBER.